Recently, a network system where a small-sized electronic circuit having a radiocommunication facility is added to a sensor and various pieces of information in the real world is input to an information processor at real time (hereinafter called a sensor network system) is researched. As for the sensor network system, the wide applications are considered, and for example, technique for regularly monitoring biometric information such as a pulse and positional information by a small-sized electronic circuit acquired by integrating a wireless circuit, a processor, a sensor and a battery, transmitting the result of monitoring to a server and others by radiocommunication and determining a condition based upon the result of monitoring is proposed.
To make the sensor network system widely practicable, the electronic circuit where the radiocommunication facility, the sensor and a power source such as the battery are mounted (hereinafter called a sensor node) that requires no maintenance for a long time and can continue to transmit measured data is demanded.
Service on the current Internet is only open to service on virtual space; however, the sensor network system is essentially different from the current Internet in that the sensor network system is in harmony with real space. If the sensor network system can be in harmony with the real space, various service of a type depending upon status such as time and a position can be realized. Traceability can be realized by connecting versatile objects existing in the real space to a network, and social needs demanding safety in wide meaning and needs for making stock management and office work efficient can be coped with (for example, refer to JP-A No. 2003-122798).